Many ophthalmic laps in the past have been shaped or cut by a lengthwise oscillating, chisel-shaped scraper. These devices are accompanied by much vibration which, when reduced to a tolerable level, produces an undesirably slow operation.
More remotely, the lap was horizontally disposed atop a vertical spindle (which might be rocked or moved in a small circle) while a circle of lens blanks were rotated against the lap by a horizontal drive shaft.* Such spindle constructions are long gone. FNT *U.S. Pat. Nos. 1,201,833; 1,221,858; 3,352,066.
Attempts have been made to design a device wherein either the lap or tool could be coupled to the side of a high speed vertical spindle. However making the lap or its carrying spindle radially positionable, imparts more instability to the whole assembly. Also, close positioning of the lap to the spindle axis (so as to produce a steep-radius curve on the lense) may result in the rear of the lap holder abutting the cutter when rotation is attempted.